The present invention relates generally to electrical power distribution systems, and more particularly to an electrical power track system employing a novel track and gripper member which enable cooperative connection to facilitate connection of an associated electrical load to a single circuit or to a selected one of a two circuit system.
Electrical power track systems of the type employing an elongated track having a plurality of longitudinally extending conductors or bus bars accessible to enable releasable engagement by electrical power contacts carried by a gripper or tap member are generally known. See, for example, U.S. Pat. Nos. 3,639,885 to Yoshiya, 3,832,503 to Crane, and 4,032,208 to Berkenhoff, each of which discloses a track lighting system employing an elongated track having an internal channel providing access to longitudinal conductors so that internal insertion of electrical contacts carried by a gripping or tap member into the longitudinal channel facilitates connection of the contacts and an associated load in a single electrical circuit. Other electrical power track systems are known which facilitate selective connection of an electrical load to either one of a plurality of different circuits carried by a common track carrier. See, for example, U.S. Pat. No. 3,848,715 to Hesse, 3,980,368 to Fremont and 4,181,388 to Donato. An example of a track lighting system employing a rotatable gripper or tap member adapted to be placed over a track in straddling fashion and rotated so as to effect contact between internally directed electrical contacts and externally exposed longitudinal conductors carried by the track is exemplified by U.S. Pat. No. 3,437,579 to Wilson.
For the most part, the known electrical power track systems exhibit a significant drawback in that the tracks and associated longitudinal conductors or bus bars are generally accessible through straight-in insertion or penetration of an electrically conductive instrumentality, such as a metal object, with the result that serious electrical shock may occur to an unknowing child or to a careless adult. A corollary to this adverse safety drawback is that these power track systems have failed to meet generally accepted safety requirements, and have thus failed to receive safety certification for commercial and private use, as by Underwriters Laboratories, Inc. U.S. Pat. Nos. 4,099,817 and 4,178,382, both issued to the present applicant, disclose track lighting arrangements which substantially overcome the aforementioned drawbacks of most electrical power track systems by inhibiting straight-in access to the electrical conductors or bus bars carried by the tracks.